summaryrefslogtreecommitdiff
path: root/src/diff_driver.c
blob: bc3518991c881adadd7f0345d4791ee921b0240f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
/*
 * Copyright (C) the libgit2 contributors. All rights reserved.
 *
 * This file is part of libgit2, distributed under the GNU GPL v2 with
 * a Linking Exception. For full terms see the included COPYING file.
 */
#include "common.h"

#include "git2/attr.h"

#include "diff.h"
#include "diff_patch.h"
#include "diff_driver.h"
#include "strmap.h"
#include "map.h"
#include "buf_text.h"
#include "config.h"
#include "repository.h"

GIT__USE_STRMAP

typedef enum {
	DIFF_DRIVER_AUTO = 0,
	DIFF_DRIVER_BINARY = 1,
	DIFF_DRIVER_TEXT = 2,
	DIFF_DRIVER_PATTERNLIST = 3,
} git_diff_driver_t;

typedef struct {
	regex_t re;
	int flags;
} git_diff_driver_pattern;

enum {
	REG_NEGATE = (1 << 15) /* get out of the way of existing flags */
};

/* data for finding function context for a given file type */
struct git_diff_driver {
	git_diff_driver_t type;
	uint32_t binary_flags;
	uint32_t other_flags;
	git_array_t(git_diff_driver_pattern) fn_patterns;
	regex_t  word_pattern;
	char name[GIT_FLEX_ARRAY];
};

#include "userdiff.h"

struct git_diff_driver_registry {
	git_strmap *drivers;
};

#define FORCE_DIFFABLE (GIT_DIFF_FORCE_TEXT | GIT_DIFF_FORCE_BINARY)

static git_diff_driver global_drivers[3] = {
	{ DIFF_DRIVER_AUTO,   0, 0, },
	{ DIFF_DRIVER_BINARY, GIT_DIFF_FORCE_BINARY, 0 },
	{ DIFF_DRIVER_TEXT,   GIT_DIFF_FORCE_TEXT, 0 },
};

git_diff_driver_registry *git_diff_driver_registry_new()
{
	git_diff_driver_registry *reg =
		git__calloc(1, sizeof(git_diff_driver_registry));
	if (!reg)
		return NULL;

	if (git_strmap_alloc(&reg->drivers) < 0) {
		git_diff_driver_registry_free(reg);
		return NULL;
	}

	return reg;
}

void git_diff_driver_registry_free(git_diff_driver_registry *reg)
{
	git_diff_driver *drv;

	if (!reg)
		return;

	git_strmap_foreach_value(reg->drivers, drv, git_diff_driver_free(drv));
	git_strmap_free(reg->drivers);
	git__free(reg);
}

static int diff_driver_add_patterns(
	git_diff_driver *drv, const char *regex_str, int regex_flags)
{
	int error = 0;
	const char *scan, *end;
	git_diff_driver_pattern *pat = NULL;
	git_buf buf = GIT_BUF_INIT;

	for (scan = regex_str; scan; scan = end) {
		/* get pattern to fill in */
		if ((pat = git_array_alloc(drv->fn_patterns)) == NULL) {
			return -1;
		}

		pat->flags = regex_flags;
		if (*scan == '!') {
			pat->flags |= REG_NEGATE;
			++scan;
		}

		if ((end = strchr(scan, '\n')) != NULL) {
			error = git_buf_set(&buf, scan, end - scan);
			end++;
		} else {
			error = git_buf_sets(&buf, scan);
		}
		if (error < 0)
			break;

		if ((error = regcomp(&pat->re, buf.ptr, regex_flags)) != 0) {
			/*
			 * TODO: issue a warning
			 */
		}
	}

	if (error && pat != NULL)
		(void)git_array_pop(drv->fn_patterns); /* release last item */
	git_buf_free(&buf);

	/* We want to ignore bad patterns, so return success regardless */
	return 0;
}

static int diff_driver_xfuncname(const git_config_entry *entry, void *payload)
{
	return diff_driver_add_patterns(payload, entry->value, REG_EXTENDED);
}

static int diff_driver_funcname(const git_config_entry *entry, void *payload)
{
	return diff_driver_add_patterns(payload, entry->value, 0);
}

static git_diff_driver_registry *git_repository_driver_registry(
	git_repository *repo)
{
	if (!repo->diff_drivers) {
		git_diff_driver_registry *reg = git_diff_driver_registry_new();
		reg = git__compare_and_swap(&repo->diff_drivers, NULL, reg);

		if (reg != NULL) /* if we race, free losing allocation */
			git_diff_driver_registry_free(reg);
	}

	if (!repo->diff_drivers)
		giterr_set(GITERR_REPOSITORY, "Unable to create diff driver registry");

	return repo->diff_drivers;
}

static int diff_driver_alloc(
	git_diff_driver **out, size_t *namelen_out, const char *name)
{
	git_diff_driver *driver;
	size_t driverlen = sizeof(git_diff_driver),
		namelen = strlen(name),
		alloclen;

	GITERR_CHECK_ALLOC_ADD(&alloclen, driverlen, namelen);
	GITERR_CHECK_ALLOC_ADD(&alloclen, alloclen, 1);

	driver = git__calloc(1, alloclen);
	GITERR_CHECK_ALLOC(driver);

	memcpy(driver->name, name, namelen);

	*out = driver;

	if (namelen_out)
		*namelen_out = namelen;

	return 0;
}

static int git_diff_driver_builtin(
	git_diff_driver **out,
	git_diff_driver_registry *reg,
	const char *driver_name)
{
	int error = 0;
	git_diff_driver_definition *ddef = NULL;
	git_diff_driver *drv = NULL;
	size_t idx;

	for (idx = 0; idx < ARRAY_SIZE(builtin_defs); ++idx) {
		if (!strcasecmp(driver_name, builtin_defs[idx].name)) {
			ddef = &builtin_defs[idx];
			break;
		}
	}
	if (!ddef)
		goto done;

	if ((error = diff_driver_alloc(&drv, NULL, ddef->name)) < 0)
		goto done;

	drv->type = DIFF_DRIVER_PATTERNLIST;

	if (ddef->fns &&
		(error = diff_driver_add_patterns(
			drv, ddef->fns, ddef->flags | REG_EXTENDED)) < 0)
		goto done;

	if (ddef->words &&
		(error = regcomp(
			&drv->word_pattern, ddef->words, ddef->flags | REG_EXTENDED)))
	{
		error = giterr_set_regex(&drv->word_pattern, error);
		goto done;
	}

	git_strmap_insert(reg->drivers, drv->name, drv, error);
	if (error > 0)
		error = 0;

done:
	if (error && drv)
		git_diff_driver_free(drv);
	else
		*out = drv;

	return error;
}

static int git_diff_driver_load(
	git_diff_driver **out, git_repository *repo, const char *driver_name)
{
	int error = 0;
	git_diff_driver_registry *reg;
	git_diff_driver *drv = NULL;
	size_t namelen;
	khiter_t pos;
	git_config *cfg = NULL;
	git_buf name = GIT_BUF_INIT;
	git_config_entry *ce = NULL;
	bool found_driver = false;

	if ((reg = git_repository_driver_registry(repo)) == NULL)
		return -1;

	pos = git_strmap_lookup_index(reg->drivers, driver_name);
	if (git_strmap_valid_index(reg->drivers, pos)) {
		*out = git_strmap_value_at(reg->drivers, pos);
		return 0;
	}

	if ((error = diff_driver_alloc(&drv, &namelen, driver_name)) < 0)
		goto done;

	drv->type = DIFF_DRIVER_AUTO;

	/* if you can't read config for repo, just use default driver */
	if (git_repository_config_snapshot(&cfg, repo) < 0) {
		giterr_clear();
		goto done;
	}

	if ((error = git_buf_printf(&name, "diff.%s.binary", driver_name)) < 0)
		goto done;

	switch (git_config__get_bool_force(cfg, name.ptr, -1)) {
	case true:
		/* if diff.<driver>.binary is true, just return the binary driver */
		*out = &global_drivers[DIFF_DRIVER_BINARY];
		goto done;
	case false:
		/* if diff.<driver>.binary is false, force binary checks off */
		/* but still may have custom function context patterns, etc. */
		drv->binary_flags = GIT_DIFF_FORCE_TEXT;
		found_driver = true;
		break;
	default:
		/* diff.<driver>.binary unspecified or "auto", so just continue */
		break;
	}

	/* TODO: warn if diff.<name>.command or diff.<name>.textconv are set */

	git_buf_truncate(&name, namelen + strlen("diff.."));
	git_buf_put(&name, "xfuncname", strlen("xfuncname"));
	if ((error = git_config_get_multivar_foreach(
			cfg, name.ptr, NULL, diff_driver_xfuncname, drv)) < 0) {
		if (error != GIT_ENOTFOUND)
			goto done;
		giterr_clear(); /* no diff.<driver>.xfuncname, so just continue */
	}

	git_buf_truncate(&name, namelen + strlen("diff.."));
	git_buf_put(&name, "funcname", strlen("funcname"));
	if ((error = git_config_get_multivar_foreach(
			cfg, name.ptr, NULL, diff_driver_funcname, drv)) < 0) {
		if (error != GIT_ENOTFOUND)
			goto done;
		giterr_clear(); /* no diff.<driver>.funcname, so just continue */
	}

	/* if we found any patterns, set driver type to use correct callback */
	if (git_array_size(drv->fn_patterns) > 0) {
		drv->type = DIFF_DRIVER_PATTERNLIST;
		found_driver = true;
	}

	git_buf_truncate(&name, namelen + strlen("diff.."));
	git_buf_put(&name, "wordregex", strlen("wordregex"));
	if ((error = git_config__lookup_entry(&ce, cfg, name.ptr, false)) < 0)
		goto done;
	if (!ce || !ce->value)
		/* no diff.<driver>.wordregex, so just continue */;
	else if (!(error = regcomp(&drv->word_pattern, ce->value, REG_EXTENDED)))
		found_driver = true;
	else {
		/* TODO: warn about bad regex instead of failure */
		error = giterr_set_regex(&drv->word_pattern, error);
		goto done;
	}

	/* TODO: look up diff.<driver>.algorithm to turn on minimal / patience
	 * diff in drv->other_flags
	 */

	/* if no driver config found at all, fall back on AUTO driver */
	if (!found_driver)
		goto done;

	/* store driver in registry */
	git_strmap_insert(reg->drivers, drv->name, drv, error);
	if (error < 0)
		goto done;
	error = 0;

	*out = drv;

done:
	git_config_entry_free(ce);
	git_buf_free(&name);
	git_config_free(cfg);

	if (!*out) {
		int error2 = git_diff_driver_builtin(out, reg, driver_name);
		if (!error)
			error = error2;
	}

	if (drv && drv != *out)
		git_diff_driver_free(drv);

	return error;
}

int git_diff_driver_lookup(
	git_diff_driver **out, git_repository *repo, const char *path)
{
	int error = 0;
	const char *value;

	assert(out);
	*out = NULL;

	if (!repo || !path || !strlen(path))
		/* just use the auto value */;
	else if ((error = git_attr_get(&value, repo, 0, path, "diff")) < 0)
		/* return error below */;
	else if (GIT_ATTR_UNSPECIFIED(value))
		/* just use the auto value */;
	else if (GIT_ATTR_FALSE(value))
		*out = &global_drivers[DIFF_DRIVER_BINARY];
	else if (GIT_ATTR_TRUE(value))
		*out = &global_drivers[DIFF_DRIVER_TEXT];

	/* otherwise look for driver information in config and build driver */
	else if ((error = git_diff_driver_load(out, repo, value)) < 0) {
		if (error == GIT_ENOTFOUND) {
			error = 0;
			giterr_clear();
		}
	}

	if (!*out)
		*out = &global_drivers[DIFF_DRIVER_AUTO];

	return error;
}

void git_diff_driver_free(git_diff_driver *driver)
{
	size_t i;

	if (!driver)
		return;

	for (i = 0; i < git_array_size(driver->fn_patterns); ++i)
		regfree(& git_array_get(driver->fn_patterns, i)->re);
	git_array_clear(driver->fn_patterns);

	regfree(&driver->word_pattern);

	git__free(driver);
}

void git_diff_driver_update_options(
	uint32_t *option_flags, git_diff_driver *driver)
{
	if ((*option_flags & FORCE_DIFFABLE) == 0)
		*option_flags |= driver->binary_flags;

	*option_flags |= driver->other_flags;
}

int git_diff_driver_content_is_binary(
	git_diff_driver *driver, const char *content, size_t content_len)
{
	git_buf search = GIT_BUF_INIT;

	GIT_UNUSED(driver);

	git_buf_attach_notowned(&search, content,
		min(content_len, GIT_FILTER_BYTES_TO_CHECK_NUL));

	/* TODO: provide encoding / binary detection callbacks that can
	 * be UTF-8 aware, etc.  For now, instead of trying to be smart,
	 * let's just use the simple NUL-byte detection that core git uses.
	 */

	/* previously was: if (git_buf_text_is_binary(&search)) */
	if (git_buf_text_contains_nul(&search))
		return 1;

	return 0;
}

static int diff_context_line__simple(
	git_diff_driver *driver, git_buf *line)
{
	char firstch = line->ptr[0];
	GIT_UNUSED(driver);
	return (git__isalpha(firstch) || firstch == '_' || firstch == '$');
}

static int diff_context_line__pattern_match(
	git_diff_driver *driver, git_buf *line)
{
	size_t i, maxi = git_array_size(driver->fn_patterns);
	regmatch_t pmatch[2];

	for (i = 0; i < maxi; ++i) {
		git_diff_driver_pattern *pat = git_array_get(driver->fn_patterns, i);

		if (!regexec(&pat->re, line->ptr, 2, pmatch, 0)) {
			if (pat->flags & REG_NEGATE)
				return false;

			/* use pmatch data to trim line data */
			i = (pmatch[1].rm_so >= 0) ? 1 : 0;
			git_buf_consume(line, git_buf_cstr(line) + pmatch[i].rm_so);
			git_buf_truncate(line, pmatch[i].rm_eo - pmatch[i].rm_so);
			git_buf_rtrim(line);

			return true;
		}
	}

	return false;
}

static long diff_context_find(
	const char *line,
	long line_len,
	char *out,
	long out_size,
	void *payload)
{
	git_diff_find_context_payload *ctxt = payload;

	if (git_buf_set(&ctxt->line, line, (size_t)line_len) < 0)
		return -1;
	git_buf_rtrim(&ctxt->line);

	if (!ctxt->line.size)
		return -1;

	if (!ctxt->match_line || !ctxt->match_line(ctxt->driver, &ctxt->line))
		return -1;

	if (out_size > (long)ctxt->line.size)
		out_size = (long)ctxt->line.size;
	memcpy(out, ctxt->line.ptr, (size_t)out_size);

	return out_size;
}

void git_diff_find_context_init(
	git_diff_find_context_fn *findfn_out,
	git_diff_find_context_payload *payload_out,
	git_diff_driver *driver)
{
	*findfn_out = driver ? diff_context_find : NULL;

	memset(payload_out, 0, sizeof(*payload_out));
	if (driver) {
		payload_out->driver = driver;
		payload_out->match_line = (driver->type == DIFF_DRIVER_PATTERNLIST) ?
			diff_context_line__pattern_match : diff_context_line__simple;
		git_buf_init(&payload_out->line, 0);
	}
}

void git_diff_find_context_clear(git_diff_find_context_payload *payload)
{
	if (payload) {
		git_buf_free(&payload->line);
		payload->driver = NULL;
	}
}